An acoustic piano employs various systems for transmitting energy from a finger or actuator input force into an auditory, vibrational force. The transmission system, commonly called the piano action, or action, is a network of levers, cushions and hammers that accepts finger/actuator input force through a collection of pivotal levers, known as piano keys, or keys. The piano keys and piano action focus this input force into rotating hammers of proportional density that are positioned to strike against tensioned wire strings. The piano hammers and their corresponding piano strings are both carefully constructed to match their acoustic properties, resulting in a tapered or graduated “scale” of components that cumulatively produce a multiple note span of musical frequencies. The piano strings act as media through which vibrational energy is transferred into an amplifier such as a soundboard, or electric speaker, where it ultimately is converted into audible sound.
Pianos can produce a wide range of volumes. Large pianos can further expand this range to include very loud sounds, such as heard in concert pianos that are expected to broadcast over an orchestra without the assistance of electric amplification. Pianos are present in many households, schools, institutions, etc. Inevitably, this proximity of sound-producing instruments creates situations where sound control and reduction are necessary. Many piano manufacturers offer pianos with sound level reducing mechanisms that selectively restrict volume level. In upright or vertical pianos, these mechanisms typically include a rail that shifts the position of the piano hammers relative to the strings, moving them closer together so that the hammers strike the strings with less kinetic energy. This type of soft pedal rail or hammer resting rail reduces the piano volume to a level of sound calculated to avoid disruption of neighboring environments such as apartments, practice rooms, etc.